Docker DCA Online Practice Questions and Exam Preparation

Docker DCA Online Questions & Answers

• Question 161:

  The Kubernetes yaml shown below describes a clusterIP service.

  

  Is this a correct statement about how this service routes requests?

  Solution: Traffic sent to the IP of this service on port 8080 will be routed to port 80 in a random pod with the label aPP: nginx.

  A. Yes
  B. No
  A. Yes

  ---

  Explanation/Reference:

  Traffic sent to the IP of this service on port 8080 will be routed to port 80 in a random pod with the label app: nginx is a correct statement about how this service routes requests. A clusterIP service is a type of service that exposes an internal IP address that is only reachable within the cluster. A clusterIP service routes requests to pods based on their labels and selectors. In this case, the service has a selector app: nginx, which means it will route requests to any pod that has the label app: nginx. The service also has a port mapping from 8080 to 80, which means it will forward requests from port 8080 on the service IP to port 80 on the pod IP. The service will use a round-robin algorithm to distribute requests among the pods that match the selector.

• Question 162:

  Can this set of commands identify the published port(s) for a container? Solution: `docker container inspect", docker port'

  A. Yes
  B. No
  A. Yes

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  Explanation/Reference:

  This set of commands can identify the published port(s) for a container. The docker container inspect command shows low-level information about a container in JSON format. This information includes the network settings of the container, such as the port bindings and exposed ports. The docker port command shows the public port(s) that are mapped to a private port inside the container. By using these two commands, you can identify the published port(s) for a container.

• Question 163:

  You want to provide a configuration file to a container at runtime. Does this set of Kubernetes tools and steps accomplish this? Solution: Mount the configuration file directly into the appropriate pod and container using the .spec.containers.configMounts key.

  A. Yes
  B. No
  B. No

  ---

  Explanation/Reference:

  This set of Kubernetes tools and steps does not accomplish this, because there is no such key as .spec.containers.configMounts in the pod specification. According to the official documentation, the correct key to use for mounting a configuration file directly into a container is .spec.containers.volumeMounts, which requires a corresponding volume definition in .spec.volumes. References: https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod- configmap/ #add-configmap-data-to-a-volume https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.22/#container-v1-core

• Question 164:

  Will this command mount the host's '/data' directory to the ubuntu container in read-only mode? Solution: 'docker run --add-volume /data /mydata -read-only ubuntu'

  A. Yes
  B. No
  B. No

  ---

  Explanation/Reference:

  This command will not mount the host's `/data' directory to the ubuntu container in read-only mode, because it has several syntax errors and missing options. According to the official documentation, the correct command should be:

  docker run --volume /data:/mydata:ro --read-only ubuntu The errors and missing options are:

  The --add-volume flag does not exist and should be replaced by --volume or -v to mount a host directory as a data volume.

  The --volume flag requires a colon (:) to separate the host directory and the container directory, not a space.

  The --read-only flag applies to the whole container's file system, not just the mounted volume.

  To make the volume read-only, a :ro suffix should be added to the --volume flag.

  The ubuntu image name should be the last argument of the command.

• Question 165:

  Which of the following commands will ensure that overlay traffic between service tasks is encrypted?

  A. docker service create --network --secure
  B. docker network create -d overlay --secure
  C. docker network create -d overlay -o encrypted=true
  D. docker service create --network --encrypted
  C. docker network create -d overlay -o encrypted=true

• Question 166:

  Which command interactively monitors all container activity in the Docker engine?

  A. docker system logs
  B. docker system events
  C. docker container events
  D. docker container logs
  B. docker system events

• Question 167:

  You set up an automatic pruning policy on a DTR repository to prune all images using Apache licenses. What effect does this have on images in this repository?

  A. Matching images are untagged once they are older than the pruning threshold set in the repository's Settings tab.
  B. Matching Images are untagged during the next prune job.
  C. Matching images are deleted during the next prune Job.
  D. Matching images are untagged during the next prune job, and subsequently deleted once they are older than the pruning threshold set in the repository's Settings tab.
  A. Matching images are untagged once they are older than the pruning threshold set in the repository's Settings tab.

• Question 168:

  Will this command ensure that overlay traffic between service tasks is encrypted? Solution: docker network create -d overlay --secure

  A. Yes
  B. No
  B. No

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  Explanation/Reference:

  This command will not ensure that overlay traffic between service tasks is encrypted, because it uses an invalid option for enabling encryption. According to the official documentation, there is no such option as --secure for the docker network create command. The correct option to use is -o encrypted=true.

• Question 169:

  The Kubernetes yaml shown below describes a networkPolicy.

  

  Will the networkPolicy BLOCK this traffic?

  Solution: a request issued from a pod lacking the tier: api label, to a pod bearing the tier:

  backend label

  A. Yes
  B. No
  B. No

  ---

  Explanation/Reference:

  The networkPolicy will not block this traffic because it does not apply to pods that have the tier: backend label. The networkPolicy only applies to pods that have the tier: frontend label, as specified by the podSelector field. Pods that have the tier: backend label are not affected by this networkPolicy and can receive traffic from any source.

• Question 170:

  You are troubleshooting a Kubernetes deployment called api, and want to see the events table for this object.

  Does this command display it?

  Solution: kubectl logs deployment api

  A. Yes
  B. No
  B. No

  ---

  Explanation/Reference:

  Using kubectl logs deployment api does not display the events table for this object. The kubectl logs command shows the logs of a pod or a container in a pod, but it does not show the events related to the deployment object. To see the events table for this object, you need to use kubectl describe deployment api.